Question

A spinner has 20 total spaces that are either blue or red. The spinner is spun, and a die is rolled. If the probability of landing on a blue space AND a 3 is 10.83%, how many blue spaces are there on the spinner?

Answer 1

Explanation:

Remark

We have to assume that the die is a cube.

We know that getting a 3, if the die is fair, is 1 chance out of 6 = 1/6

We don't know how many blues there are on the spinner, but we do know that the number of them is over 20. So that's x/20

Now multiply the left side to get the combined probability. x/20 * 1/6. The result is 10.83/ 100

Solution

(x/20) * (1/6) = 10.83/100

x / 120 = 10.83/100 Multiply both sides by 120

x = 10.83 * 120 / 100

x = 12.996 which is going to round to 13

The blue spaces = 13